The fastest communication data rate currently specified by the Institute of Electrical and Electronics Engineers (IEEE) over structured copper cabling is 10 gigabit/second (Gbps) per the IEEE802.3ba standard. The structured cabling infrastructure called out in this standard is based on twisted pair cabling and RJ45 connectivity which calls for plugs and jacks having four pairs of corresponding contacts arranged in a generally parallel 1-8 in-line fashion with one of the pairs split around the center pair. This type of structured copper cabling specified by the IEEE includes four balanced differential pairs over which Ethernet communication takes place. Compliant channels will also meet the TIA568 Category 6A (CAT6A) specifications for cable, connectors, and channels. These CAT6A components and channels provide 500 MHz of bandwidth for data communication across 100 meter links.
In 2010, the IEEE ratified a new standard, IEEE802.3an, for high speed Ethernet communication at speeds of 40 Gbps and 100 Gbps. While this new standard called for both fiber and copper media, the only supported copper media was a short (7 m) twin-ax based copper cable assembly. No provisions were made for twisted pair structured copper links. Additionally, the proposed standard includes a specification that has Medium Dependent Interface (MDI) components such as magnetics and printed circuit board (PCB) traces. This PHY (Physical Layer Transceiver) to PHY specification creates a challenging task for designers.
Traditionally, copper connectivity has been associated with a number of benefits including lower cost, ease of field terminability, and ease of mateability between corresponding connectors. This has prompted the investigation of the feasibility of transmitting 40 Gbps over a structured copper channel. One approach to this is detailed in the International Electrotechnical Commission (IEC) 60603-7-71 standard, which incorporates two “modes” of operation to allow for backward compatibility with RJ45 style plugs and a higher bandwidth style plug, sometimes referred to as “ARJ45”, with 4 pairs of contacts isolated in “quadrants.” When mated with an RJ45 plug, the connector must provide the necessary electrical crosstalk compensation to comply with the RJ45 rated standard such as CAT6A. When mated with an IEC 60603-7-71 plug, the connector must provide the corresponding isolated contact locations.
This dual-mode functionality is achieved by sharing the two outermost pairs of RJ45 contacts, while also grounding the middle two pairs of RJ45 contacts and providing two new pairs of isolated contacts in case of mating with an IEC 60603-7-71 plug. In total there are six pairs of contacts in the connector, of which only four are used depending on which style plug the connector is mated with.
The presence of the extra pairs and the mechanical operation of the connector results in a challenging electrical design due to the potential parasitic coupling between unused contacts and/or unwanted compensation circuitry. Thus, there exists a continued need for further development and advancement of communication connectors, including PCB-mounted versions, which may allow for increased transfer rates while retaining backward compatibility with the RJ45 standard. Furthermore, since communication connectors are often used in systems which incorporate adjacent connector configurations, there is a continuing need for improved system designs which improve system performance, increase the ease of manufacturability, and provide robust electrical mating points.